For the downsizing and high performance of electronic devices, the mounting technology as well is required to intend the high performance. Presently, in the mounting packages used for the elements of PCs, servers, etc., decoupling capacitors, etc. are arranged around the elements for the current supply upon source voltage drops, noise removal, etc. This function becomes increasingly important as the elements become speedy and have lower drive voltage.
To speedily make the current supply, it is necessary to make low the impedance of the decoupling capacitor and the source power supply system. For this end, a capacitor of high capacitance and low inductance, and the decrease of the capacitor interconnection length are required. The arrangement position of the capacitor directly below the element is most effective, and a package with the capacitor incorporated is required. This is effective also for lowering the cost, and such package is expected.
As the method of incorporating a capacitor are proposed various methods, such as the method of burying the capacitor components in a package, the method of forming a capacitor film, etc. Among them, the method of patterning films to form a capacitor permits the capacitor to be arranged selectively at a required part inside the circuit, and it is most expected to use this method to incorporate the film capacitor.
Presently, the widely generally used package is formed of an epoxy resin-based material. On the other hand, the capacitor is formed of a barium titanate-based dielectric ceramics. The process temperature for forming ceramics is not less than 1000° C., and it is considered impossible to directly introduce ceramic film during the process of manufacturing the resinous package whose heat resistance temperature is about 250° C.
The followings are examples of related: Japanese Laid-open Patent Publication No. 2002-194560; Japanese Laid-open Patent Publication No. 2003-277949; Y. Imanaka and J. Akedo, Technique of RF passive element integration by aerosol deposition, Ceramics, Vol. 39, No. 8, pp. 584-589 (2004); and Y. Imanaka, N. Hayashi, M. Takenouchi and J. Akedo, Aerosol deposition for post-LTCC, Journal of the European Ceramic Society 27 (2007), pp. 2789-2795.
As the process of forming dielectric ceramic film are sputtering method, sol-gel method, etc. The film deposited by sputtering method is subjected to thermal processing at a temperature of not less than about 600° C. to crystallize and densify the as-deposited amorphous film. The film deposited by sol-gel method is also subjected to thermal processing for evaporating the solvent after alkoxide liquid has been applied. Resultantly, thermal shrinkage, thermal stresses, etc. are generated in such thermal processing, and cracks and micro-cracks are often formed in the film. Especially when the film thickness is thin, it is difficult to form film of good quality.
In the method of forming a capacitor structure by a dielectric ceramics film above a substrate having a smooth surface, such as a silicon wafer, a sapphire waver or others, the film stress is not uniformed due to the presence of the substrate in the base, and in a multilayer of a certain number of layers, inter-layer peelings often takes place. The presence of the substrate in the base lowers the degree of freedom of leading out the terminal, and the impedance of the whole containing systems, such as the arrangement of the lead electrode, etc. often increases.